Lids mounted by threading onto jars or bottles are difficult to tighten or loosen by hand. Numerous devices have been developed for alleviating the difficulty in such task. Some of such devices are hand-held and others are fixedly mounted under the cupboard or a shelf. The hand-held devices commonly have an adjustable gripping means which is operative for grasping the lid of the jar firmly, and a handle which the user may then turn relative to the jar so as to loosen or tighten the lid. Such hand-held devices are usually awkward to operate since the user must hold the jar or bottle firmly with one hand while turning the handle of the device with the other hand. Such operation is often rather frustrating due to that the jar or bottle can not be held firmly with one hand which invariably is the hand with the weaker grip, or the user simply does not have the dexterity or strength to carry out the operation. The mounted openers are more convenient and easier to operate since the user may grip the jar or bottle firmly with both hands and turning it relative to the mounted opener. However, most of such devices are designed only for opening the jar or bottle lid and they can not be used for tightening the same. Tightening of jar or bottle lid is particularly essential such as in the canning operation in which the lid must be secured firmly to an air-tight state in order to assure the preservation of the food for a long period of time without spoilage.
In U.S. Design Pat. No. 258,192 to Robert W. Maloney, it shows a jar opener of a V-shaped wedge mounted under the kitchen cupboard. Two serrated blades are mounted one on each side of the wedge with the teeth on one blade skewed in one direction and the teeth of the other blade skewed in the opposite direction. When the lid of the jar is urged against the blades, the teeth of the two blades, skewed in the opposite directions, would cooperate to grip the lid firmly by biting into the lid side wall while the jar is being turned so as to open the lid. Such device is effective for opening the lid but it can not operate to tighten the latter. Furthermore, the side surface of the lid would be inherently marred by the teeth of the blades biting into the lid side wall and creating rather sharp burr therein. Such sharp burr can cause harmful cuts or scratches in the user's hand if the lid is gripped or touched unsuspectingly thereafter.
U.S. Pat. No. 4,262,560 by Charles C. Hoffberger shows an opener which may be used for opening as well as for securing the lid of a bottle or jar. The device is in the form of a wedge having a rubber lining mounted on the inside surface of both sides of the wedge. A rigid bar is mounted at the center of the wedge to divide the wedge into two halves. The lid of the jar may be opened or closed by chocking the lid against a selected half of the wedge. The main drawback of the Hoffberger device is that the centre dividing bar is mounted to the supporting top plate by adhesive. Since the dividing bar is subjected to a very high sideways shearing force when the lid of the jar is forced against the wedge and turned in the operation, the dividing bar would dislodge from the mounting either readily or after a short period of use. Even if the bar were mechanically mounted solely or in addition to the adhesive, it would invariably still be distorted under the extremely high sideways pushing or side shearing force, thus rendering the device inoperative. Furthermore, the device is relatively and awkwardly large in size due to the requirement essentially of having to provide two wedges, one for opening and the other for closing the jar lid. Still furthermore, since the rubber liners are fixedly mounted on the inside surface of the wedge, they are difficult to repair and/or replace.